Device and method for ablation of cardiac tissue

Abstract

Methods for delivering precise amounts of fluid into cardiac tissue for the purpose of facilitating ablation of the tissue along a desired lesion line. One method injects fluid through a hollow needle. The injected fluid can be a highly conductive fluid injected in conjunction with radiofrequency ablation to create an ablative virtual electrode. The injected conductive fluid can provide deeper and narrower conduction paths and resulting lesions. Radiofrequency ablation can be performed at the same time as the fluid injection, using the injection device as an electrode, or subsequent to the fluid injection, using a separate device. In some methods, the injected fluid is a protective fluid, injected to protect tissue adjacent to the desired lesion line. Fluid delivery can be endocardial, epicardial, and epicardial on a beating heart. The present methods find one use in performing maze procedures to treat atrial fibrillation.

Description

RELATED APPLICATIONS[0001]The present application claims priority to U.S. provisional patent application Ser. No. 60 / 381,217, filed on May 16, 2002, titled DEVICE AND METHOD FOR ABLATION OF CARDIAC TISSUE, herein incorporated by reference in its entirety. The present invention is related commonly assigned U.S. patent application Ser. No. 10 / 356,909, filed on Feb. 3, 2003, titled DEVICE AND METHOD FOR NEEDLE-LESS INTERSTITIAL INJECTION OF FLUID FOR ABLATION OF CARDIAC TISSUE.FIELD OF THE INVENTION[0002]The present invention relates generally to the field of devices for cardiac surgery, and more specifically to devices for ablation of cardiac tissue.BACKGROUND OF THE INVENTION[0003]The present invention is directed toward treatment of tachyarrhythmias, which are heart rhythms in which a chamber or chambers of the heart exhibits an excessively fast rhythm. In particular, the present invention is directed toward treatment of tachycardias, which are due to the presence of ectopic foci wi...

AI Technical Summary

Benefits of technology

[0017]In yet another aspect of the invention, a device as described above is utilized in order to deliver a protective fluid in order to protect certain areas of cardiac tissue, such as tissue near vessels and valves. For example, a hypotonic fluid can be used as a protective fluid in order to increase the electrical impedance of the tissue to be protected relative to the surrounding tissues, essentially insulating the protected tissue from the electrical current of the radiofrequency ablation device. This aspect of the invention can be combined with one or more of the other aspects of the invention in which a conductive liquid is delivered to a first portion of cardiac tissue along a desired lesion line and a protective fluid is delivered to a second portion of cardiac tissue spaced apart from the desired lesion line. This can be readily accomplished by a device having a plurality of spaced-apart needles with centrally located needles delivering the conductive liquid and other needles on one or both sides of the centrally located needles which deliver the protective fluid. As the radiofrequency ablation device, such as the Cardioblate pen, is advanced along the desired lesion line a narrower and deeper lesion would result with this technique.

Problems solved by technology

Sometimes aberrant conductive pathways develop in heart tissue, which disrupt the normal path of depolarization events.

For example, anatomical obstacles in the atria or ventricles can disrupt the normal propagation of electrical impulses.

These wavelets, called “reentry circuits,” disrupt the normal activation of the atria or ventricles.

Otherwise, tissue will be unnecessarily destroyed.

In addition, the heart is in close proximity to nerves and other nervous tissue and the destruction of this tissue will result in severe harm to the patient.

Although successful at treating AF, the surgical maze procedure is quite complex and is currently performed by only a few skilled cardiac surgeons in conjunction with other open heart procedures.

Problems faced by these methods, however, include (a) the creation of continuous, linear lesions in the atria for the prevention of atrial fibrillation, (b) minimization of clotting and thromboembolism, (c) the effect of heat loss due to circulating blood, (d) minimization of lesion width and minimization of atrial debulking, (e) conforming to an irregular myocardial thickness, (f) adaptability to a variety of lesion geometries and (g) usefulness from either the endocardial surface of an open heart, or the epicardial surface of a beating heart.

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